The story is told as a series of memories by Jacob Jankowski, a ninety or ninety-three year-old man who lives in a nursing home.
As the memories begin, Jacob Jankowski is twenty-three years old and preparing for his final exams as a Cornell University veterinary student when he receives the news that his parents were killed in a car accident. Jacob’s father was a veterinarian and Jacob had planned to join his practice. When Jacob learns that his father was deeply in debt because he had been treating animals for free as well as mortgaging the family home to provide Jacob an Ivy League education, he has a breakdown and leaves school just short of graduation. In the dark of night, he jumps on a train only to learn it is a circus train. When the owner of the circus, Uncle Al, learns of his training as a vet, he is hired to care for the circus animals.
The head trainer, August, is a brutal man who abuses the animals in his care as well as the people around him. Alternately, he can be utterly charming. Jacob develops a guarded relationship with August and his wife, Marlena, with whom Jacob falls in love. August is suspicious of their relationship and beats Marlena and Jacob. Marlena subsequently leaves August, which is the precipitating event leading to the ultimate demise of the Benzini Brothers circus.
As the story climaxes, several circus workers who were redlighted off the train come back and release the animals causing a stampede during the performance. (Redlighting refers to throwing circus workers off the moving train as punishment or in order to avoid paying them). In the ensuing panic, August is killed. As a result of this incident, which occurred during a circus performance, the circus is shut down. Marlena and Jacob leave, along with several circus animals, and begin their life together